This invention relates to sensing devices, and more particularly to gas flow sensing devices. This invention is particularly directed to a gas flow sensing device that indicates one or more selected rates of gas flow, yet at a maximum sensed flow will not substantially restrict the gas flow and thereby cause undesirable back pressure.
There are many applications wherein it is necessary to sense the flow of gas, often these situations require the sensing of either a no flow or maximum flow condition. For example, in venting certain gases to the ambient, it is often necessary to know if there is any flow at all, and also to know if the flow has reached or exceeded a certain selected maximum permissible rate. This sensing also often must be done with respect to a corrosive or explosive gas.